Temperature control for centrifugal analyzer

ABSTRACT

Disclosed is a method and apparatus for providing close temperature control for the spinning, rotating cuvette and sample distributing disc assembly of a high speed centrifugal analyzer or comparable rotating head device by circulating a temperature conditioning fluid through the rotating assembly. This method of temperature control assures rapid thermal response of the rotor and sample so that precise temperature control and stability is provided for the rotor, cuvettes and test specimens in the rotating assembly. The conditioning fluid may be any fluid and it may either raise or lower the temperature of the assembly.

United States Paten Maclin et al.

[ 1 Apr. 17, 1973 TEMPERATURE CONTROL FOR CENTRIFUGAL ANALYZER [73] Assignee: Electro-Nucleonics, Inc, Essex County, NJ,

[22] Filed: Feb. 19, 119711 [21] Appl. No.: 116,884

[52] US. Cl ..233/111, 233/26, 233/1 D [51] Int. Cl. B0411: 15/02 [58] Field of Search ..210/178, 179, 211, 210/361, 362; 233/26, 27, 28, 46, 47 R, 1 A, 12, 45, l 1

[56] References Cited UNITED STATES PATENTS 2,936,110 5/1960 Cohen ..233/13 3,108,955 10/1963 Boyland ..233/27 1,527,076 2/1925 Peck ..233/l1 2,560,988 7/1951 Ruda ..233/26 3,255,805 6/1966 Bechard .233/l1 X 1,000,540 8/1911 Neikirk ..2l0/2ll 1,735,523 11/1929 2,435,023 l/l948 3,268,078 8/1966 Muggli ..2l0/l79X Primary Examiner George H. Krizmanich Attorney-Henry T. Burke, P. E. Henninger, Lester W. Clark, Gerlad W. Griffin, Thomas P. Moran, Howard J. Churchill, Bradlee Boal, Christopher C. Dunham and Robert Scobey' Disclosed is a method and apparatus for providing close temperature control for the spinning, rotating cuvette and sample distributing disc assembly of a high speed centrifugal analyzer or comparable rotating head device by circulating a temperature conditioning fluid through the rotating assembly. This method of temperature control assures rapid thermal response of the rotor and sample so that precise temperature control and stability is provided for the rotor, cuvettes and test specimens in the rotating assembly. The conditioning fluid may be any fluid and it may either raise or lower the temperature of the assembly.

11 Cl, 7 Drawing Figures PATENTED 3. 727. 832

SHEET 1 OF 5 l INVENTORS 1 ERA/551' MACL /A/ BY ABE J. PERLE PATENTED APR 1 71973 TEMP.

DEV/AT/OM C TEMP. DEVIATIOU SHEET 5 [IF 5 Tia. 5.

TIME (MI/U.) a

. I El I? SHROUD HEATER DIRECT L/QU/D HEAT/N6 TIME (MIN) 0 i 5 'P '4 f ALUMINUM couswucmu CUVETTE TEFLOM CONSTRUCTION CUVETTE INVENTORS EQA ESf M/lCL/A/ BY 5 J. PE/PLE TEMPERATURE CONTROL FOR CENTRIFUGAL ANALYZER BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION tained within a tight bandwidth in the reagents and 1 samples present on the disc, to assure high repeatability and accuracy during the analysis of temperature sensitive reactions.

Temperature control to a high degree of precision (plus or minus 0.2 F) is required for some chemical reactions in order to provide precise rates of reaction. Further, the temperature of samples must be maintained within this degree of precision relative to the temperature of the standards and the blanks that are carried on the rotating assembly to assure maximum analytical accuracy.

Previous methods of temperature control relied on heaters mounted external to the rotating disc. In such a configuration, i.e., heaters mounted externally, heat is conducted and radiated from the stationary shroud housing assembly to the rotating disc assembly through the air gap between the rotating disc and the housing. This method of heat transfer is ineffective and produces a long thermal time constant. The reason for this is that the conductive thermal resistance between the heat source and the heated part (the rotor) is relatively high. Further, radiated thermal energy is minimal because of the limited thermal gradient between the housing and the rotating disc. Therefore heat transfer byradiation is of little consequence. Present methods do not provide as close control and rapid response of sample to rotor temperature as the method proposed herein and hence they require a pre-conditioning of the reagents to assure controlled reaction temperatures.

The method proposed herein provides temperature control of the rotor by direct contact of the tempering fluid with the rotor (similar to a water jacket cell) by passing the tempering fluid through a rotating seal mechanism.

In this method, the tempering fluid is introduced into the rotating disc (rotor) through a system of seals, through passages in the supporting shaft, radially through the rotary disc, around the cuvette area and it is returned through the support shaft. Additional temperature control is obtained by directing water, used to wash the cuvettes, which is previously tempered through the inside of the cuvettes and subsequently to a drain, thereby imparting a further degree of tempera ture conditioning to the inside surface of the cuvettes. The use of thermally conditioned wash water in this fashion prevents the chilling of the cuvettes during the washout procedure that may be employed between successive operations, assuring that the follow-up sample will not be adversely cooled or heated upon its introduction to the rotating cuvettes system. This further assures a maximum sample through-put rate since no extra machine time is required for extensive thermal conditioning of the sample to the required controlled reaction temperature.

To further reduce the thermal resistance between the tempering fluid and the sample, the cuvette walls can be constructed of a high thermal conductivity material such as aluminum. This material may then be coated with a polymer such as TEFLON or polypropylene to improve the chemical inertness of the cell. An optical path through the cell is provided by quartz windows sealed against the metallic walls.

These and other objectives and advantages of the invention will become apparent to those skilled in the art upon reading the following detailed description in light of the drawings forming a part hereof. In'the drawings 0 like reference numerals indicate like parts, and;

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view through a preferred form of centrifuge taken along the center line thereof;

FIG. 2 is an enlarged fragment of the upper and lower end of the rotor shaft intended to more clearly illustrate the conditioning fluid conduits;

FIG. 3 is a fragmentary vertical sectional view through the rotor of a modified form;

FIG. 4 is a plan view of the rotor disc, showing also the path of the conditioning fluid about the cuvettes;

FIG. 5 is a plan view of an alternate rotating disc, showing the tempering fluid paths therein;

FIG. 6 is a curve plotted to compare the rotor temperature response for direct rotor heating and shroud heating; and,

FIG. 7 is a curve plotted to show the temperature response of the samples in polymer coated aluminum cuvettes structure as compared to TEFLON cuvettes structure.

DETAILED DESCRIPTION By reference to FIG. 1 of the drawings, it will be seen that the operative elements of the centrifugal analyzer 10 are housed in an external jacket 12 supported on a base casting 14. At its upper end the jacket is formed as a bottom shroud section 16 which together with a top shroud section 18 comprises a shroud assembly which houses a rotor assembly 20. The shroud sections 16 and 18 are separably held together by a clamping ring 19. The rotor assembly is driven by a motor 22 whose rotor is attached to a rotor shaft 24. The lower end of the rotor shaft is seated in a seal assembly 26 which is fixed to the base casting 14 by means of a spider 28. The rotor shaft is hollow and contains therein a pair of concentric tubes 30 and 32 forming a conditioning fluid inlet duct 34 and a conditioning fluid outlet duct 36 (see also FIG. 2).

The seal assembly 26 is internally grooved to accommodate TEF LON seals 38 against which the rotor shaft operates. The seal assembly 26 also provides a wash water inlet connection 40, a conditioning fluid inlet connection (not shown) and a conditioning fluid discharge connection 42. The wash water inlet connection 40 communicates with the lower open end of the rotor shaft 24. The conditioning fluid inlet connection (not shown) communicates with an annular duct 44, while the conditioning fluid discharge connection 42 communicates with an annular duct 46. The conditioning fluid inlet duct 36 opens into the annular conditioning fluid inlet 44 and the conditioning fluid outlet duct 36 opens into the annular conditioning fluid discharge 46.

The rotating shaft 24 is stabilized by upper bearings 48 and lower bearings 50 against which it operates. The

rotor 52 of the motor is held to the rotor bushing 54 and a rotor nut 56, both of which embrace the rotor shaft and contact respective opposite ends of the rotor. The stator of the motor abuts a shoulder 58 of the jacket 12 and is is supported at its lower end by a stator support ring 60 which is secured to the bottom end of the jacket 12 by a plurality of machine screws 62. This is an optional design. The rotating system can also use an external motor and a belt drive to cause rotation of the rotor assembly.

The upper end of the rotor shaft terminates in a shaft platform 64. The rotor assembly 20 is attached to the shaft platform by means of a plurality of machine screws 66.

From the foregoing it can be seen that when the motor 22 is energized, the rotor shaft will be driven in rotation and the rotor assembly 20 will be spun.

The rotor assembly 20 consists of a dish shaped supporting disc 68 to which is fixed a cuvette assembly 70. The connection may be by means of a plurality of machine screws 72. The cuvette assembly 70 is in the form of an annulus (FIG. 4) consisting of a plurality of cuvette areas (cell) 74. The structure of the individual cuvettes is best seen in FIG. 1.

The cuvette annulus rests on a bottom gasket 80 and is surmounted by a top gasket 82. The hold-down ring 84 (FIG. 1) completes the cuvette assembly. If desired the shroud assembly may be provided with supplementary temperature control devices such as the heaters 84, 86 and 88 (FIG. 3), and the water that exists from the rotating seal system can be circulated around the shroud to further temper the thermal inputs into the rotating system.

Within the cuvette annulus, the supporting disc 68 provides a space for receiving a specimen and reagent holder 90. The specimen and reagent holder provides a plurality of wells 94 and 96 equal in number to the number of cuvettes. Each of the wells 94 and 96 discharges into its related cuvette. The wells 94 and 96 are separate for separately receiving reagent and specimen, respectively. The holder 90 may be charged with specimen and reagent externally of the centrifuge and then inserted therein while the centrifuge is at rest.

The cuvette assembly and the specimen and reagent holder are sealed when required by a closure cap 98. A spring pressed collar 100 located between the inner wall of the closure cap 98 and the reagent and specimen holder 90 holds the latter firmly against the supporting disc 68.

The bottom shroud section 16 has a wash water outlet 102 for discharging wash water into a wash water drain 104. A slip ring assembly 106 may be fixed to the rotor shaft for connection to an external control temperature or monitoring system. A quartz window 108 and holes in the hold down ring 84 and disc 68 permit viewing of the chemical reaction or sedimentation of the samples under observation of a spectrophotometer or colorimeter, for example.

At the onset of operation conditioning fluid is admitted to the conditioning fluid inlet duct 34 (see FIGS. 2 and 3). The conditioning fluid may be any fluid. It will ordinarily be preconditioned to a desired temperature. The conditioning fluid will rise in the duct 34 and enter tempering fluid inlet paths 112 in the supporting disc 68 (FIG. 5). The tempering fluid aths 112 extend to the periphery of the supporting 18 68 and then through transverse apertures 114, thereby introducing the conditioning fluid to the cuvette assembly. Flow of the conditioning fluid is shown in FIG. 4. The escape of conditioning fluid (see FIG. 5) is by way of transverse apertures 120 and channels 122 (see also FIG. 3) which communicate with the conditioning fluid discharge duct 36.

An abundant supply of wash water is now admitted through the wash water inlet 40. This will rise through the hollow rotor shaft and discharge through passages 110 at the top of the shaft which communicates with chamber 102a (FIG. 3). After purging the cuvette assembly the wash water will be discharged through the wash water outlet 102. The wash water may be temperature conditioned in order to impart an additional temperature condition to the assembly. The reagent and specimen holder may be loaded into the centrifuge and the closure cap 98 may now be applied and test begun.

The curve of FIG. 6 shows that the direct fluid heating of the assembly as taught herein will raise the temperature of the cuvette assembly a given number of degrees in 2 minutes whereas if shroud heating alone is employed, as in FIG. 3, 13 minutes is required to attain the same temperature deviation.

The cuvettes of prior art devices have been constructed of TEFLON. These had a poor temperature response. It is a purpose of this invention to construct the cuvettes of a high thermal conductivity material such as aluminum which may be coated with a polymer such as TEFLON or polypropylene to improve the chemical inertness of the cuvette. The latter form of cuvette provides for better temperature response of the sample as clearly shown by the curve plotted in FIG. 7. This curve demonstrates that with aluminum cuvettes a sample temperature deviation of, say, 5 1 C can be attained in 2 minutes whereas TEFLON cuvettes require 16 minutes for the sample to attain the same temperature deviation.

Having now described the invention, that for which a patent is sought is the following.

We claim:

1. In a temperature control and wash fluid system for a centrifugal analysis device having a rotor assembly and cuvettes therein, a rotor shaft for rotating said rotor assembly the improvement comprising a plurality of passages extending through said rotor shaft, means for supplying a temperature conditioning fluid to one of said shaft passages, a temperature conditioning passage in said rotor assembly for receiving said temperature conditioning fluid from said one rotor passage and applying said temperature conditioning fluid to regions adjacent said cuvettes to control the temperature thereof and discharging said temperature conditioning fluid to another one of said rotor passages, means for supplying a wash fluid to a third one of said rotor passages, a wash fluid passage in said rotor assembly for receiving said wash fluid and applying it to said cuvettes, and means for discharging said wash fluid from said rotor assembly. 

1. In a temperature control and wash fluid system for a centrifugal analysis device having a rotor assembly and cuvettes therein, a rotor shaft for rotating said rotor assembly the improvement comprising a plurality of passages extending through said rotor shaft, means for supplying a temperature conditioning fluid to one of said shaft passages, a temperature conditioning passage in said rotor assembly for receiving said temperature conditioning fluid from said one rotor passage and applying said temperature conditioning fluid to regions adjacent said cuvettes to control the temperature thereof and discharging said temperature conditioning fluid to another one of said rotor passages, means for supplying a wash fluid to a third one of said rotor passages, a wash fluid passage in said rotor assembly for receiving said wash fluid and applying it to said cuvettes, and means for discharging said wash fluid from said rotor assembly. 